High-pressure X-ray investigation of zincite ZnO single crystals using diamond anvils with an improved shape

2006 ◽  
Vol 39 (2) ◽  
pp. 169-175 ◽  
Author(s):  
Heidrun Sowa ◽  
Hans Ahsbahs
Keyword(s):  
High Pressure ◽  
Single Crystals ◽  
Axial Ratio ◽  
High Pressure Cell ◽  
Pressure Derivative ◽  
Orientation Relations ◽  
Diamond Anvils ◽  
Large Opening ◽  
Murnaghan Equation

A high-pressure cell for single-crystal investigations requires large opening angles. If it does not contain any beryllium but only two diamonds mounted on steel backing plates, normally only lower pressures can be attained without risk of disruption of the diamond anvils [Ahsbahs (2004).Z. Kristallogr.219, 305–308]. In order to enable pressures up to at least 10 GPa, specially shaped anvils were designed. In a first study with such anvils, the high-pressure behaviour of zincite ZnO was investigated up to the transition pressure of about 9.5 GPa. A slight decrease of the axial ratioc/awith increasing pressure was observed. The fit of the Birch–Murnaghan equation of state gave a bulk modulusK= 146.5 (8) GPa with a fixed pressure derivativeK′ = 4. During the phase transformation, the single crystals were destroyed. The pronounced preferred orientation of the obtained material, however, enabled the determination of the orientation relations between the low-pressure wurtzite-type and the high-pressure NaCl-type phase. The orientation relations are similar to those in CdS and CdSe.

scholarly journals Compressibility and Phase Stability of Iron-Rich Ankerite

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 607
Author(s):  
Raquel Chuliá-Jordán ◽  
David Santamaria-Perez ◽  
Javier Ruiz-Fuertes ◽  
Alberto Otero-de-la-Roza ◽  
Catalin Popescu
Keyword(s):  
High Pressure ◽  
Density Functional ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
High Pressure Phase ◽  
Stable Phase ◽  
Pressure Derivative ◽  
Reversible Phase Transition ◽  
Murnaghan Equation ◽  
Pressure Phase

The structure of the naturally occurring, iron-rich mineral Ca1.08(6)Mg0.24(2)Fe0.64(4)Mn0.04(1)(CO3)2 ankerite was studied in a joint experimental and computational study. Synchrotron X-ray powder diffraction measurements up to 20 GPa were complemented by density functional theory calculations. The rhombohedral ankerite structure is stable under compression up to 12 GPa. A third-order Birch–Murnaghan equation of state yields V0 = 328.2(3) Å3, bulk modulus B0 = 89(4) GPa, and its first-pressure derivative B’0 = 5.3(8)—values which are in good agreement with those obtained in our calculations for an ideal CaFe(CO3)2 ankerite composition. At 12 GPa, the iron-rich ankerite structure undergoes a reversible phase transition that could be a consequence of increasingly non-hydrostatic conditions above 10 GPa. The high-pressure phase could not be characterized. DFT calculations were used to explore the relative stability of several potential high-pressure phases (dolomite-II-, dolomite-III- and dolomite-V-type structures), and suggest that the dolomite-V phase is the thermodynamically stable phase above 5 GPa. A novel high-pressure polymorph more stable than the dolomite-III-type phase for ideal CaFe(CO3)2 ankerite was also proposed. This high-pressure phase consists of Fe and Ca atoms in sevenfold and ninefold coordination, respectively, while carbonate groups remain in a trigonal planar configuration. This phase could be a candidate structure for dense carbonates in other compositional systems.

Phase segregation and the effect of high pressure on the electro-transport in Y0.95Pr0.05Ba2Cu3O7-δ single crystals

2014 ◽  
Vol 28 (17) ◽  
pp. 1450142 ◽  
Author(s):  
Ruslan V. Vovk ◽  
Georgij Ya. Khadzhai ◽  
Oleksandr V. Dobrovolskiy
Keyword(s):  
High Pressure ◽  
Critical Temperature ◽  
Single Crystals ◽  
Oxygen Content ◽  
Pressure Effect ◽  
Phase Segregation ◽  
Sample Volume ◽  
Pressure Derivative ◽  
High Hydrostatic Pressures ◽  
High Pressure Effect

The effect of high hydrostatic pressures of up to 17 kbar on the basal ab-plane conductivity of lightly praseodymium-doped (x ≈ 0.05) Y 1-x Pr x Ba 2 Cu 3 O 7-δ single crystals with unidirectional twin boundaries (TBs) is investigated. It is observed that the application of a high pressure leads to a doubling of the pressure derivative value dTc/dP for Pr -doped samples compared to non-doped YBa 2 Cu 3 O 7-δ samples with optimal oxygen content. Possible mechanisms of the high pressure effect on the critical temperature Tc and the phase segregation in the sample volume are discussed.

High pressure single crystal X-ray diffraction study on α-quartz

1999 ◽  
Vol 214 (6) ◽  
Author(s):  
J. Kim-Zajonz ◽  
S. Werner ◽  
H. Schulz
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
The Other ◽  
Data Sets ◽  
Theoretical Studies ◽  
Intensity Data ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
Murnaghan Equation

AbstractSingle crystal X-ray diffraction experiments onVolumina of the unit cell were determined to 13.1 GPa, by combining the data with data taken from the literature; the bulk modulus and pressure derivative calculate to 38.7(3) GPa and 5.2(1) respectively according to a Birch-Murnaghan equation of state.Intensity data were collected at 10.9(1), 12.0(1), 12.1(1), 12.6(1) and 13.1(1) GPa. From the five intensity data sets, one was collected using synchrotron radiation at HASYLAB/DESY and the other four using a conventional X-ray tube. Results show that the SiOIn addition to the five intensity data sets collected, X-ray diffraction experiments were carried out up to 19.3 GPa in order to address the question of when the structure undergoes amorphization. It was observed that up to 19.3 GPa, no pressure-induced amorphization takes place. This result is in agreement with studies carried out on powder quartz and theoretical studies.

Determination of high-pressure phase equilibria of Fe2O3 using the Kawai-type apparatus equipped with sintered diamond anvils

2009 ◽  
Vol 94 (2-3) ◽  
pp. 205-209 ◽  
Author(s):  
E. Ito ◽  
H. Fukui ◽  
T. Katsura ◽  
D. Yamazaki ◽  
T. Yoshino ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Equilibria ◽  
High Pressure Phase ◽  
Diamond Anvils ◽  
Sintered Diamond ◽  
Pressure Phase ◽  
Type Apparatus

Einkristallröntgenstrukturanalyse an Quecksilberchromat(VI): Hg3O2CrO4 / Single Crystal X-Ray Structure Determination of a Mercury Chromate(VI): Hg3O2CrO4

1995 ◽  
Vol 50 (1) ◽  
pp. 47-50 ◽  
Author(s):  
Th. Hansen ◽  
Hk. Müller-Buschbaum ◽  
L. Walz
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Single Crystals ◽  
Structure Determination ◽  
Trigonal Symmetry ◽  
X Ray ◽  
Group D ◽  
Symmetry Space ◽  
Symmetry Space Group

Single crystals of Hg3CrO6 have been prepared by high pressure techniques (3600 bar oxygen, 600 °C). Hg3CrO6 crystallizes with trigonal symmetry, space group D63—P3212, a = 7.137(1), c = 10.017(2) Å, Z = 3. Nearly linear O—Hg—O dumb-bells are connected in planes, forming strongly puckered nets of six-membered rings. Each Hg6O6 ring is centered by a CrO4 tetrahedron; the CrO4 tetrahedra are arranged in two equally occupied split positions.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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